During the drilling of a wellbore, various fluids are used in the well for a variety of functions. The fluids may be circulated through a drill pipe and drill bit into the wellbore and then may subsequently flow upward through wellbore to the surface. Wellbore fluids used during drilling may act to lubricate and cool rotary drill bits, prevent blowouts by providing hydrostatic pressure to balance any high-pressure formation fluids that may suddenly enter the wellbore, and remove cuttings from the wellbore.
Following the drilling of a wellbore, completions operations may involve placing a pipe string or casing to line the well. Well casings of various sizes may be used, depending upon depth, desired hole size, and geological formations encountered. The casing may serve several functions, including providing structural support to the wellbore to prevent the formation walls from caving into the wellbore. The casing may, in some instances, be stabilized and bonded in position within the wellbore. However, because drilling fluids are generally not settable, a portion of the drilling fluid may be removed from the wellbore so that the casings may be set in place by a primary cementing operation. Before cementing operations commence, engineers may determine the volume of cement to be placed in the wellbore (often with the help of a caliper log) and the physical properties of the cement needed, including density and viscosity.